andrea, back to you. >> ron allen, thanks so much. and nbc's lester holt is live in watertown. lester, we've been saying but it can't be overemphasized, this is unprecedented. an entire metropolitan area, a major american city and all of its suburbs, shut down. no mass transit. everyone staying indoors at the behest of the governor, voluntarily, at the behest of the governor, their mayor and their state police. >> you know, andrea, i've been racking my brain, i've worked news in new york, san francisco, chicago, in the network over 30 years, i can't think of anything like this. 9/11 i remember them shutting the airplanes down. i've covered hostage situations, standoffs. nothing like this where a metropolitan area is put on hold. at first it sounds so bizarre. if you just think through the events that we have witnessed, it makes a lot of sense. here's two individuals who set these bombs that cut down innocent people, killed three, maimed others.